Coating mixture for pack rolling



Patented July 23, 1935 UNITED STATES PATENT OFFICE No Drawing.

l'lOlaims.

This invention relates to the coating of metallic sheets or "breakdowns" for the purpose of preventing adhesion of superposed sheets during the process of pack rolling, by which the sheets are 6 elongated until they have the desired thickness.

Heretofore, various attempts have been made to provide a satisfactory coating for the abutting faces of the sheets of a pack to be rolled for the purpose of preventing adhesion of the sheets when heated and rolled. Such abutting faces, heretofore, have been coated with various compounds which, to some extent, resisted adhesion of the sheets to one another, but difliculty was experienced in preventing such adhesion of the sheets and, at the same time, obtaining sheets of desired quality after rolling such as sheets which are clean, stainless, white in appearance, and have a close grained and high, glossy surface or finish. The use of a plurality of difierent chemically uncombined forms of carbon in a fermented solution is disclosed and claimed in my prior Patent No. 1,915,391, issued June 7, 1983.

An object of this invention is to provide an improved coating mixture for treating the metal sheets of packs for pack rolling, by which adhesion of the sheets to one another during rolling will be eifectively prevented; with which sheets may be obtained that, after rolling, will be su-' perior in appearance and quality to those heretoi'ore obtained; which will give dependable and uniform results; and which will be relatively simple and inexpensive.

I have now discovered that superior results in I C pack rolling may be obtained by the use of my improved coating composition which is applied to the sheets of the pack before the sheets are heated and rolled. In accordance with my discovery, I prepare the coating mixture of finely divided carbon in a plurality of different, chemically uncombined forms that are mixed into and can'ied by a liquid suspending medium. When this mixture is applied to the faces of the sheets, it forms an adherent coating that protects the faces of the sheets during the heating and rolling operations, and produces an improved finish on the faces of the sheets.

Preferably, one of these chemically, uncombined forms of carbon to be used is graphite, and the amorphous and crystalline forms thereof are the most satisfactory. While the flab graphite may be used, I have found it less satisfactory than the amorphous or crystalline forms of the graphite. The other forms of the chemically, uncombined carbon in finely divided condition may Application June 12, 1934, Serial No. 730.!

be finely divided charcoal, and a form of carbon known under different names such as carbon black, lampblack and soot. The liquid suspension medium may be a water solution of a form of soda such as sal soda, soda ash, sodium carbonate, or bicarbonate of soda, or it may be an aqueous solution of a sugar, such as molasses or glucose, and I have found that glucose gives better results than the molasses or other sugars in that there is less discoloration of the sheets with the use oi the glucose. The various forms of soda and the sugar or glucose act especially as a mixing agent for the various forms of carbon, particularly lampblack or other soot, since it is difllcult to cause lampblack and other forms of carbon to mix with water alone. Some'other adhesive liquid may be used with the lampblack or soot, if desired. When charcoal and graphite alone are used the liquid vehicle may be water, or water with some form of soda-dissolved therein, but the glucose and soda solutions are advantageous in improving the color and quality of the rolled sheet. The soda aids in getting the various forms of carbon into mixture in the liquid vehicle, improves the quality of the rolled sheet, andmakesitpossibletouselesscarboninthe mixture. As a specific example of a coating mixture which embodies my invention or discovery, the following sample mixtures are given:

LampblacL. 101m. harcoalll lbs. Graphite- Soda. Wat: 400 gal Glucose Nona. 10 to so lbs. 400ml. Nona.

These materials in any mixtureare thoroughly mixed together. If desired, the glucose or soda g andthewatermaybeaddedtotheformsof carbon selected, and thoroughly mixed therewith. While the ingredients ofthis composition may be mixed in any desired order, or the solids all addedtotheliquidatthesametime andstirred therein, I have found that somewhat better results are obtained if the graphite is added last.

I have found that very satisfactory results may be obtained if the lampblack or other soot and the graphite are used in approximately equal pro- 10 portions, but the proportion of the charcoal may be varied throughawiderrange and maybeused to some extent to replace the lampblack or other soot. The lampblack or other soot may be entirely replaced by the finely divided charcoal, if .88

lampblack and a major amount of charcoal, it is not usually possible to obtain as glossy a finish as when more of the lampblack is used. The lampblack penetrates between the sheets somewhat better than the graphite. If desired, little or no charcoal may be used in which case a larger proportion of the soot or lampblack may advantageously be used, butsuch a mixture is more expensive than when some' charcoal is used.

After the mixture of different forms of finely divided, chemically uncombined carbon with the suspension medium has been made, the sheets to be rolled are coated with this liquid mixture and allowed to dry. The sheets are then placed in packs, heated to the rolling temperature and then rolled, during which the sheets are enlarged in area and reduced in thickness. The coating may be applied to the sheets in any suitable manner, such as by dippingthe sheets into the liquid mixture or by spraying the mixture upon the sheets. The coating mixture may, if desired, be heated so that the sheets coated therewith will dry rapidly, and the coating retained upon the sheets will remain fixed thereon while the sheets are being handled and matched up. The exposed faces of the sheets of the packs, such asthe tops'and bottom faces ofthe pack, may also be coated with the mixture in order to-protect them under the rolling pressure placed thereon during the rolling operation.

It is important that the various forms of carbon used be invery finely divided condition in order that they will be 'more easily and uniformly retained in suspension in the mixture and, consequently, more uniformly spaced upon the sheets. The finer the particles, the fewer the imperfections and indentations which will be formed on the surface of the rolled sheets and, therefore,

the higher the quality of the sheets. While graphite and charcoal in a water mixture could beusedas acoatingmixtureandwouldresultin sheets having some of the advantages of my discovery, a brighter and better sheet is obtained when the coating mixture includes amorphous carbon such as lampblack or other soot and the fine particles are carried in suspension in a soda or glucose solution.

In the heating operation, just prior to the rolling, the charcoal is the first to burn out and, when burned, leaves a slight ash which aids in keeping the iron sheets from sticking to one another. The charcoal of the mixture forming the coating also acts somewhat as a binder for the other carbon forms and aids in keeping the lampblack or other soot and the graphite particles separated or spread evenly, and thus reduces the cost of the mixture since the powdered charcoal is less expensive than the soot or lampblack and the graphite. The graphite is the best lubricant between the sheets and will withstand higher furnace temperatures before burning out, than will the lampblack or charcoal, so that the sheets so coated may be heated to a much higher temperature in the furnace before rolling than when lampblack and/or charcoal alone is used. Consequently, the sheets at the higher temperatures may be rolled more easily and perfectly and with fewer defects because less force is required to elongate the material of the sheets'at the higher temperatures.

Among the advantages resulting from the use of the improved mixture according to this invention, may be mentioned the following. The improved coating resists the formation of scale and 2,008,880 but I have found that with little or no oxides on the metal sheets during the heating of the sheets preparatory to rolling, prevents or lessens scratching of the sheets, and also the formation of the scale on the sheets in the annealing or finishing processes. The rolled sheets, after being placed in the pickling bath, come clean and white, without stains. The coating also resists the spreading of the grain of the metal in the rolling and annealing operations, producing sheets with no open surfaces and with close grain on the faces.

when the sheets are coated in accordance with this invention and then rolled, there will be no mottle or spots in the material of the sheets, such as are frequently produced by excessive charcoal or the use of charcoal alone. The sheets will be free of smoke, flashes and discoloration, will not sweat while placed in piles in the finishing department, will not rust or undergo other changes due to atmospheric conditions during storage or shipment, even though the sheets are cleaned of the'coating before shipment, because during the rolling of sheets coated in this manner, the surfaces of the sheets have been closed so thoroughly; and such a highly glossy surface produced, that it is impossible for water or moisture to get into the pores of the sheets and set up a rusting or scaling action.

Sheets coated, before rolling, in accordance with this invention, have such'a' smooth, glossy, and closed grain surface that the cost of subsequent cold rolling to provide such a surface is largely saved. The lampblack or other soot and the charcoal may be considered as a controlling agent for the graphite, to prevent slipping of the graphite, or displacement thereof. Since the sheets coated in accordance with this invention mu be heated to a higher temperature for the rolling operation, 'the sheets will not be hardened by the rolling to the extent that would Occur under excessive cold rolling, and consequently have better drawing properties than sheets heretofore possible.

It will be obvious that various changes in the proportions of parts of the ingredients, in the order of the steps and in the other details, which have been herein set forth in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention, as expressed in the appended claims.

I claim:

l. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided graphite, finely divided charcoal, and a sugar solution free of alcohol.

2. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided carbon in a plurality of different, chemically uncombined forms, one of which is graphite, and an unfermented Mar solution free of alcohol.

3. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided graphite, soot, and a suspending liquid free of alcohol. 4. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided carbon in a plurality of different, chemically uncombined forms, one of which is graphite, and an unfermented glucose solution free of alcohol.

5. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided graphite, finely divided charcoal, soot, and a li yiid suspension medium free or alcohol.

6. A mixture for use in preventing adhesion between metal sheets during pack rolling or. the like, containing finely divided graphite, finely divided charcoal, soot, and a liquid suspension medium, mixed in the proportions approximately of 10 pounds each oi graphite, and soot, 10 to 30 pounds of charcoal, and 400 gallons of liquid tree of alcohol.

7. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided carbon in a plurality o! diflerent, chemically uncombined forms, and a liquid suspending medium free of alcohol.

8. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided carbon in a plurality oi difierent, chemically uncombined forms, one of which is graphite, and another of which is lampblack, and a liquid suspending medium tree of alcohol.

9. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided carbon in three different, chemically uncombined forms, one of which is graphite, and a liquid suspending medium free of alcohol.

10. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided carbon in a plurality of different, chemically uncombined forms, said forms including graphite and at least another form selected from the group consisting of charcoal and lampblack and a liquid suspending medium free of alcohol.

11. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided carbon in a plurality or diflerent, chemically uncombined forms, and a liquid glucose suspending medium tree of alcohol.

12. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided,. chemicallyuncombined carbon in anaqueous solution of soda.

13. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided, El'Te'mically uncombined carbon in a plurality of different forms in an aqueous solution of soda.

14. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided, chemically uncombined carbon in a plurality of different forms, one 0! which is graphite, in an aqueous solution of soda.

15. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided, chemically uncombined carbon in a plurality of difierent forms, one 01' which is charcoal in an aqueous solution oi soda.

16. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, containing finely divided, chemically uncombined carbon in a plurality oi. difierent forms,

one of which is lampblack in an aqueous solution of soda.

1'1. A mixture for use in preventing adhesion between metal sheets during pack rolling or the like, said mixture containing finely divided carbon in a plurality of diilerent chemically uncombined i'orms, and an aqueous suspending liquid containing a form of sugar and soda.

MERLE-LSTOOPS. 

